British Prime Minister David Cameron (3L) speaks to Britain's Queen Elizabeth II (C) as she and Britain's Prince Philip, Duke of Edinburgh (R) arrive at the royal pavilion on Horse Guards Parade in central London on October 20, 2015 for the ceremonial welcome for Chinese President Xi Jinping and his wife Peng Liyuan on the first official day of a state visit. Chinese President Xi Jinping arrived for a four-day state visit as the government of Prime Minister David Cameron seeks stronger trade ties with the world's second-largest economy. AFP PHOTO / ADRIAN DENNIS (Photo credit should read ADRIAN DENNIS/AFP/Getty Images)